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Effect of Energy Balance and Somatotropin on Insulin-Like Growth Factor I in Serum and on Weight and Progesterone of Corpus Luteum in Heifers1

Effect of Energy Balance and Somatotropin on Insulin-Like Growth Factor I in Serum and on Weight and Progesterone of Corpus Luteum in Heifers1,M. C. Y

Effect of Energy Balance and Somatotropin on Insulin-Like Growth Factor I in Serum and on Weight and Progesterone of Corpus Luteum in Heifers1   (Citations: 21)
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Holstein heifers ( ≈1 yr old) were fed to be in negative energy balance (n = 14; NEB) or positive energy balance (n = 15; PEB) during four estrous cycles. Each heifer was given PGF2a to control the timing of fourth estrus. From 1 d after PGF2a injection until 10 d after estrus, half of the heifers were injected daily with 14 mg of somatotropin (bST), and the corpus luteum (CL) was collected on d 10. Heifers in NEB had less IGF-I in serum ( P < .01), smaller CL ( P < .01), and less progesterone in CL ( P < .01) than heifers in PEB. Exogenous bST increased ( P < .01) IGF-I in serum, but this increase was greater in heifers in PEB than those in NEB ( P < .01 for interaction of energy balance and bST). Nonethe- less, bST did not alter weight or progesterone content of the CL in either energy balance group. In addition, serum IGF-I during the first 10 d after estrus was not correlated to luteal weight and only weakly correlated (r = .3) with luteal progesterone content. We conclude that exogenous bST given during luteal development does not alter growth or progesterone content of the CL in heifers. Reduced concentration of IGF-I in serum during luteal development does not account for suppressed luteal growth and progesterone synthesis of heifers in NEB.
Published in 2010.
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    • ...Specifically, it has been suggested that an exacerbation of NEB from the cost of metabolising ammonia and urea might be responsible for the reduction in the concentration of progesterone in serum (Yung et al 1996; Walters et al 2002)...

    A Ordóñezet al. Effects of application in spring of urea fertiliser on aspects of repr...

    • ... endocrine profile of high GH levels may, however, be responsible for the extension of the luteal phase, as GH has been shown to be luteotrophic in vitro (Liebermann & Schams 1994, Wathes et al. 1995) and some studies have reported that administration of bovine somatotrophin to lactating cows can prolong the luteal phase (Schemm et al. 1990, Gallo & Block 1991, Lucy et al. 1994), although this effect was not seen in 1-year-old heifers ...

    V J Tayloret al. First lactation ovarian function in dairy heifers in relation to prepu...

    • ...Other studies reported that IGF-I concentrations in blood of cows in cNEB due to either fasting or lactating were lower compared to animals in a less negative cNEB [63, 104] and that cows selected for high milk production, thereby more at risk of non adaptation, have lower insulin concentrations during peak and mid lactation [10]...
    • ...In vivo, increased NEFA concentrations are correlated with lowered progesterone concentrations and a decrease in CL weight [104]...

    Ruurd Jorritsmaet al. Metabolic changes in early lactation and impaired reproductive perform...

    • ...Studies on luteal function of lactating dairy cows (32) and heifers (36) have shown that energy balance affects PP concentration, and it may be related to availability of precursors for steroidogenesis...
    • ...When EB is improved, more energy as VFA, such as acetate, is available for cholesterol synthesis, which might increase progesterone secretion by the CL. Negative EB not only decreases circulating progesterone, but it also decreases CL size and weight and reduces its progesterone content (36)...

    J. E. P. Santoset al. Effects of Grain Processing and Bovine Somatotropin on Metabolism and ...

    • ...Yung et al. (69) found that not only did negative EB cause a decrease in CL size, but it resulted in a decrease in progesterone within the CL as compared with cows on a higher plane of nutrition...
    • ...Yung et al. (69) noted lower levels of serum IGF-I in negative EB cows when compared with cows in positive EB. Within the follicle it may be the ratio of IGF-I to various IGFBP that determines if a follicle is to ovulate or become atretic...
    • ...Our stage of lactation differences in serum IGF-I patterns reflect differences in EB (69), and may impact gonadotropin secretion as Zurek et al. (70) found an association between IGF-I and LH pulsatility...

    F. C. Gwazdauskaset al. SYMPOSIUM: FOLLICULOGENESIS IN THE BOVINE OVARY Impact of Follicular A...

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